Abstract
Photodynamic therapy (PDT) is a skin cancer treatment alternative to chemotherapy and radiotherapy. This method exploits three elements: a phototoxic compound (photosensitizer), light source and oxygen. Upon irradiation by light of a specific wavelength, the photosensitizer generates reactive oxygen species triggering the cascade of reactions leading to cell death. The positive therapeutic effect of PDT may be limited due to low solubility, low tumor specificity and inefficient cellular uptake of photosensitizers. A promising approach to overcome these obstacles involves the use of nanocarrier systems. The aim of this initial study was to determine the potential of the application of phosphorus dendrimers as carriers of a photosensitizer—rose bengal (RB). The primary goal involved the synthesis and in vitro studies of covalent drug–dendrimer conjugates. Our approach allowed us to obtain RB–dendrimer conjugates with the use of tyramine as an aromatic linker between the carrier and the drug. The compounds were characterized by FT-IR, 1H NMR, 13C NMR, 31P NMR, size and zeta potential measurements and spectrofluorimetric analysis. The dialysis to check the drug release from the conjugate, flow cytometry to specify intracellular uptake, and singlet oxygen generation assay were also applied. Finally, we used MTT assay to determine the biological activity of the tested compounds. The results of our experiments indicate that the conjugation of RB to phosphorus dendrimers via the tyramine linker decreases photodynamic activity of RB.
Highlights
IntroductionAccording to World Health Organization (WHO), the incidence of both non-melanoma and melanoma skin cancers hasHealth been increasing over(WHO), the past the decades.Currently, between two and threeAccording to WorldOrganization incidence of both non-melanoma and million non-melanoma and 132,000 melanoma cancersCurrently, occur globally eachtwo yearand [1].melanoma skin cancersskin hascancers been increasing over the pastskin decades. betweenChemotherapy and radiotherapy are used successfully in the treatment of these types of cancer, but three million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each cause[1].many complications and side effects [2,3].Limited specificity therapies provokes yearChemotherapy and radiotherapy are used successfully in of thethose treatment of these typesthe of search for more effective treatment strategies [4]
Photodynamic therapy is based on the application of a photosensitizer that, upon irradiation by light of a specified wavelength, produces reactive oxygen species and singlet oxygen [24], the generation of which starts a cascade of reactions leading to cell death [25]
The present work demonstrates that it was possible to (1) modify the structure of rose bengal—a well-known photosensitizer used for photodynamic therapy studies—with a linker in the form of tyramine; (2) to graft selectively three modified rose bengal units onto the surface of phosphorus dendrimers of generation 1, 2 and 3 used as nanocarriers; (3) to modify these new nanoobjects via the grafting with pyrrolidino groups, followed by their protonation; (4) to study in depth their physicochemical and biological properties; (5) to point out the key role of the linker between phosphorus dendrimers and rose bengal in limiting fluorescence and phototoxic properties of the photosensitizer
Summary
According to World Health Organization (WHO), the incidence of both non-melanoma and melanoma skin cancers hasHealth been increasing over(WHO), the past the decades.Currently, between two and threeAccording to WorldOrganization incidence of both non-melanoma and million non-melanoma and 132,000 melanoma cancersCurrently, occur globally eachtwo yearand [1].melanoma skin cancersskin hascancers been increasing over the pastskin decades. betweenChemotherapy and radiotherapy are used successfully in the treatment of these types of cancer, but three million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each cause[1].many complications and side effects [2,3].Limited specificity therapies provokes yearChemotherapy and radiotherapy are used successfully in of thethose treatment of these typesthe of search for more effective treatment strategies [4]. According to World Health Organization (WHO), the incidence of both non-melanoma and melanoma skin cancers hasHealth been increasing over(WHO), the past the decades. Organization incidence of both non-melanoma and million non-melanoma and 132,000 melanoma cancersCurrently, occur globally eachtwo yearand [1]. Chemotherapy and radiotherapy are used successfully in the treatment of these types of cancer, but three million non-melanoma skin cancers and 132,000 melanoma skin cancers occur globally each cause[1]. Photodynamic therapy (PDT)therapies is a very cancer, butsafer causeand many complications and side effects [2,3]. Limited specificity of those interesting method skineffective cancer treatment therapy [5]
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